The biological cell is so advanced it can look after itself, but its not exactly smart. Except now, its all about to change. Scientists are now making cells that can perform arithmetic. Will this be the start of a living computer?

Scientists at the Swiss Federal Institute of Technology in Zurich have created biological versions of digital circuits inside two sets of embryonic kidney cells. One of it is a half adder and the other is a half subtractor. They are circuits that are capable of adding or subtracting binary numbers.

What will they be used for? The idea is that they could be used in computational devices for the body to diagnose diseases, administer drugs or even interface with other electronic devices. The research is published in Nature.

The cellular circuits, are replaced with two naturally occuring molecules, erythromycin and phloretin—which act as inputs to switch reactions in the cells on or off. The reactions cause red or green fluorescent proteins to be produced, in turn signalling the result of the calculation.

What's most amazing is that the reactions—and hence calculations—take place without interfering with the biologic function of the cells, so they can happily live and function properly inside the human body.

As with other research, this is still in its infancy, and the output of the cells currently can't be used as the input to another. But once the research team works around that it will open up the possibility of using the cells to build up complex computational devices. [Nature via New Scientist]